border-1px($color)
  position relative
  &:after
    display block
    position: absolute;
    left: 0
    bottom: 0
    width: 100%
    border-top: 1px solid $color
    content: ''

bg-image($url)
  background-image: url('img/'+$url+'@2x.png')
  @media(-webkit-min-device-pixel-ratio:3),(min-device-pixel-ratio:3){
    background-image: url('img/'+$url+'@3x.png')
  }

keyFrameAll($value)
    width $value px
    height $value px
    background-color blue
